Determinants of medical record access for an epidemiologic study

Hospital record access is often needed for epidemiologic research. In a recent study, 26 Denver-area hospitals were contacted for permission to review records. The review process, the decision regarding access, and hospital characteristics were analyzed. Hospitals with a review committee, larger hospitals, and those which reached a decision rapidly were most likely to grant access. These results may provide guidance to investigators planning studies requiring review of hospital records.

Screening for geographic heterogeneity of disease rates: application to cancer incidence in Allegheny County, Pennsylvania, 1969-71

A statistical technique for analyzing heterogeneity in rates proposed by Gail is potentially well-suited to the analysis of geographic patterns in disease incidence data. This was applied to 1969-71 cancer incidence in whites in 30 census tract aggregates within Allegheny County, Pennsylvania to ascertain its usefulness and to search for patterns. A product model, in which each area's risks are a constant multiple of one another across age groups, was found to adequately fit the observed data. The test for geographic heterogeneity indicated that 19 of 30 sex-site groupings manifested greater than chance variation across the county subunits, generally consistent with the number of outliers based on 95% confidence limits. Partitioning the heterogeneity in these sites by median income quintiles suggested a positive risk gradient with breast cancer (F) and negative risk gradients with rectal (M), pancreatic (F), lung (M), cervical (F), and bladder cancer (F). Percent foreign stock was positively associated with total cancer (M, F), colon (M, F), pancreatic (F), lung (M), and bladder cancer (M, F). The technique successfully demonstrated the accuracy of a product model, screened cancer sites meriting detailed study, and suggested several associations of median income and percent foreign stock with cancer risk.

Cancer risk among oil refinery workers. A review of epidemiologic studies

The possibility that excess cancers result from occupational exposures in oil refineries has generated a great deal of interest. Ecological studies and case-control studies in the general population have suggested a positive association between oil industry activity and cancer rates, with more direct evidence provided by studies of refinery employees. The eight investigations of cancer risks among refinery employees are critically reviewed. The methodological strengths and weaknesses of these studies are evaluated with an emphasis on the likely impact on the results. While the results are markedly inconsistent across studies, there is some suggestion of excess risks for melanoma and for brain, stomach, kidney, and pancreatic cancers. Problems with exposure characterization, latency, and potential confounding factors limit all of the studies that were reviewed.

Survey of reproductive hazards among oil, chemical, and atomic workers exposed to halogenated hydrocarbons

Several halogenated hydrocarbons are suspected of causing adverse reproductive effects. Because of such concerns, the Oil, Chemical, and Atomic Workers International Union surveyed the reproductive histories of two groups of workers. One group worked at plants engaged in the production or use of halogenated hydrocarbons (exposed) whereas the others had no such opportunity for exposure (nonexposed). Although a low response rate precludes firm conclusions, the 1,280 completed questionnaires provide useful data for generating hypotheses in this developing field of interest. A history of diagnosed cancer was reported more frequently among exposed workers. The infant mortality rate was also significantly elevated among the offspring of exposed workers. No risk gradient was observed for episodes of infertility, fetal loss, congenital defects, or low-birthweight offspring. Concerns with nonresponse, exposure characterization, possible confounding factors, and limited statistical power are addressed. The results provide further suggestions which help to direct studies of occupational reproductive risks.